In spite of the remarkable progress that has been made in the reduction of the prevalence of dental caries it continues to be the most prevalent dental disease. The results of the most recent national survey, NHANES III, indicated that by age 17 nearly 78% of U.S. residents are afflicted with dental caries. This number increase to about 85% in persons 18 years of age and older and, in addition, 50% of persons beyond 75 years of age have root surface caries involving at least one tooth. These data also indicate that young adults 18-25 years of age had an average of nearly 14 decayed, missing or filled tooth surface and that this number increases to 41 in persons 36-45 years of age. Further these numbers are not appreciably influenced by race, income level, or level of education. Although these latter numbers for caries prevalence are somewhat less than was observed in prior surveys it is quite apparent that more effective measures for the prevention and control of this disease are needed. The identification of young adults at significant risk for dental caries would permit the implementation of professional and home-use measures for the prevention and control of dental caries. Thus, the overall goal of this investigation is to develop a caries risk assessment instrument for young adults that accurately determine caries risk. The Specific Aims of this project are: (1) develop a survey instrument based upon existing knowledge and the prior experience of the team in identifying persons with significant medical risks; (2) collect preliminary data to validate the caries risk assessment instrument by conducting clinical caries examinations in young adults 18-25 years of age using two new technologies (Quantitative Light Fluorescence and ICDAS) known to be capable of detecting caries; increments within a 6- month test period; and (3) use the caries data to evaluate each component of the caries risk assessment instrument for their value in identifying persons with significant caries risk. Future large-scale investigations will be undertaken to validate the merits of the instrument.